Radio contourmeter



P. B. HUNTER RADIO CONTOURMETER Dec. 17, 1940.

Filed May 3, 1958 Zer CHARGE e'sulscns'al INVENTOR RNEY R F- W 5 w m m m I 5 M w n. I P, m

Fillllllllllll Patented Dec. 11, 1940,

rrn rsmE' nA'mo CONTOURMETER' Paul; a. Hunter, Bloomfield, N. 'J.,Iassignorj to Sperry Gyroscope Company, Inc., Brooklyn, N. Y. ,acorporationofNewYork Application May 3, 1938, s mi No. 205,686 1 ,1 Claims. (01; zsof-n This invention relates, generally, to radio means for measuring. distance,and the invention has reference, more particularly, to a novel radiocontourmeter adapted for indicating the height of an aircraft directly above the terrain'over height of the aircraft with respect to the terrain in advance of the aircraft; whereby the pilot'is' given advance information as towhether the terrain he is approaching is ascending or descending', and 'may therefore control the elevation of his craftaccordingly to avoid collision.-

While an absolute altimeter such as disclosedin applicants copending application Serial No. 151,178, filed'July 3, 1937, joint with Joseph Lyman and Francis L. Moseley, will give an accurate; indication of the height of the craft above the ground,"it' does not give any indication of the nature of the terrain aheadlof the craft and to ward which the latter is heading, with the result that especially in hilly or mountainous regions during periods of poorvisibility crashes;: are-aptto oc'cur'due, for example, to theflying of a craft from a valley toward a mountain, the-sudden change in contour'of the terrain being too great for the-craft to navigate'safely without advance information being given the pilot.

, e The principal object of the present invention is to provide a novel instrument-termed a contourmeter, which will give the pilot of a'craft advance information as to the natureof theterrain ahead so that he can maneuver his craft accordingly, whereby, forexample, should there arise a moun- I v tain ahead too high to climb over, he will have an ,35 opportunity to turn to one side or the other and hence avoid a crash. v v

Another object of the present invention lies in the provision of a novel radio contourmeter that serves to give a continuous visual,accurate indication on an instrument face of .the height of'th'e craft directly above the earth and also the relative height of the craft with respect to the terrain in advance of the craft regardless of atmosf 1 ,pheric conditionsor visibility, the said contourwhich the same is flying and also the relativetery 6, and this tube is put on momentarily at ing received by suitable radio receiver means,

means being provided and operableat the instants of propagation of said waves to cause. a cathode ray tube to operate by movementof beamsover the facejthereof to time the intervals elapsingber tween-the time of transmission and the time of reception of ,the reflected waves, the extent of movement of thecathoderay beams .over the tube face during, such intervals being a measure of the desired distances, the tube face ,being calibrated to directly indicate such, distances.

Other-objects and advantages will become. apparent from the specification, taken in connection with the accompanying drawinghwher'ein the invention is embodied in concrete form. 5

In the drawing. A a i Fig. :1 is a wiring diagram illustrating the nave contourmeter of the present invention. l

Fig. 2 is a schematic viewin elevation, illustrating-an aircraft equipped withthe novel con-1 g tourmeter. v

Fig. .3is a face view of the cathoderay'tube of' .7 Fig.1." 7

Fig. 4. is a graphillustrating an operating characteristic of the invention. 1 I Similar characters of reference are used in all of the above figuresto-indicatecorresponding parts Referring now to thedrawing, the reference numeral I designates an aircraft shown provided so with directional transmitter andreceiver antennae, one pair comprisingtransmitter andreceiver antennae directed straight downwardlyand another pair comprisingtransmitter and receiver antennae directed forwardlyand downwardlyat any desired angle with the vertical such, for example, as 60, the downwardly directed antenna reflectors being designated 2 and the forwardly and downwardly directed antenna reflectors being designated-3 in- Fig. 2 of the drawing.

Referring particularly to Fig. 1,-a transmitter 4 of the ultra high frequency type has ancscillator tube 5 that is normally biased off by a hat regular intervals, such as twenty-five times per second, due to theaction of the relaxation generator This generator comprises agrid controlled tube 8 whose plate is supplied from a battery 9 through a resistance II. A condenser I2 is connected atone side to theplate supply of, tube 8 at a point-between the plate electrodeof. the, tube and the resistor II and is connected at its other side to the tube cathode. The minimum 5 plate voltage at which tube 8 will discharge may be varied by varying the grid bias as determined by the adjustment of a grid potentiometer arm I! and, if desired, by supplying suflicient grid bias,

6 the tube may be prevented from passing current.

Assuming that the grid has control, the condenser II will be charged by current supplied from battery 8 through resistor ll. While condenser is charging, the plate voltage applied to 1 tube I is steadily raised until it reaches a critical value, whereupon the grid loses control and condenser I2 is suddenly discharged through tube 8 and a resistor I! included between the tube cathode and condenser l2. Due to the approximate short circuit effect of the tube discharge on the condenser [2, the potential of this condenser, and.

hence that of the tube plate, drops below that necessary to sustain the discharge and before the condenser can recharge due to the presence of resistor u, with the result that tube a shuts off and its grid again gains control preparatory to the repetition of the cycle, which is repeated preferably twenty-five to thirty times a second.

when the tube 8 discharges the condenser I 2, a relatively substantial voltage is suddenly supplied across the resistor ,as shown by the vertical line V in Fig. 4. The ends of this resistor are connected in the cathode grid circuit of the oscillator tube 5 by leads I5, and hence this voltage is applied tothe grid of the tube and, overcoming the bias of battery 8, causes this tube to function momentarily to thereby cause the transmitter l to send ofl U. H. F. electromagnetic waves from its directional transmitter antenna l6, positioned, for example, in the downwardly directed reflector 2, whereby these waves are directed toward the ground. Since the bias of battery 6 is such as to shut off transmitter 4 except when the voltage V is at its peak value shown in Fig. 4, and as this voltage V decays rapidly at first, only one or perhaps a few ultra high frequency electromagnetic waves of effective amplitude will be transmitted by equipment I at each moment of 4! transmission, so that there will be no standing waves in space whenusing this equipment, but instead at intervals of one-twenty-flfth of a second, for example, a short electromagnetic wave or waves will be sent off which will travel to the 60 ground and will .be partially reflected to the receiver antenna 3|, thereby exciting the receiver momentarily, the apparatus of this invention serving to time the interval required for the wave or waves to .travel to the earth and back to the apparatus.

Similarly, a transmitter 4', operating at a somewhat different frequency from transmitter 4, is controlled by a relaxation generator I so as to send of! U. H. F. electromagnetic waves so from its directional transmitter antenna I" which may be located, for example, within the parabolic reflector 3 directed forwardly and downwardly at the angle 0, such as with respect to the vertically directed waves emitted as by antenna I.

A cathode ray tube H has its elements supplied from a-potentiometer I. connected across a D. 0. supply. This tube is shown as provided with two transversely separated electron emitting areas or cathodes l9, l9, which are electrically connected together. This tubeis shown as provided with two independent control grids 20 and 20' for independently controlling the electron streams emitted from the cathodes ll and I9, respectively. This tube is shown pro- 1 ll adjacent the distance scales 2!, 2|.

vided with two sets of vertical deflecting plates 2| and 2| for respectively deflecting the electron beams emitted from cathodes I-l and II. The beams projected from these cathodes are normally/biased above the visible part of the 5 face 22 of the tube by batteries 23 and 23'. Battery 23' is connected through leads 24' and 2! and a portion of resistor M to the vertical defleeting plates 2|, of tube ll. item as the discharge voltage appears across the resistor 10 7' II or the resistor I4, the. polarity of the deflecting plates II or 21', as the case may be, is reversed and the beam is moved instantly to the bottom of the face 12, and thereupon starts to rise at arate depending upon the rate of de- 15 cay of the voltage across the correspondingresistor ll'or I4, and this may be varied by varying the magnitude of this resistor.

The curves 2! of Fig. 4 show typical rates of decay of voltage V during the period of discharge 1. of condenser l2 or l2. Thus, as the voltage V decays, the cathode ray beam is caused to move upwardly due to the action of the battery 23 or 23", as the case may be. thereby producing luminous paths 28 and 28' on the face of tube 3.

The beams move upwardly rapidly at flrst and with gradually decreasing rapidity, so that scales 2!, 29' are provided with their length or distance indications arranged substantially logarithmicalno ly and with the greater spacing of indications at the bottom of the scale so as to permit a more accurate determination of altitude and contour at points near the earth.

The radio receiver 30 is tuned to the same freas quency as the transmitter 4 and the antenna ll of this receiver is positioned alongside of the antenna I 6, though it is shielded therefrom. these antennae bein preferably mounted within two of the downwardly directed reflectors 2 arranged alongside one another with shielding means therebetween. As soon as the receiver 8| receives the reflected wave sent out, by the transmitter I, a voltage pulse is impressed on the secondary of output transformer 32 from detector 5 tube 33, causing the diodetube 34 to operate and create a voltage drop across a resistor ll in its plate cathode circuit, thereby charging a condenser 35 connected in parallel with resistor 3i and depressing the voltage on the control grid 50 28 of the cathode ray tube l'l, inasmuch as one side of the condenser 3i isconnected to the grid ll by a lead 31 and the other side of this grid, connected tothe cathode, is also connected by a lead a to a point on potentiometer I! that is 55 of lower potential than the voltage supply through a lead 3! to the tube cathode 10. Hence, the cathode ray beam passing between plates 2| is cut off and the length of the fluorescentline 20 indicates on scale 29 the height of the craft above do the ground. By the time that condenser 36 has discharged and the cathode ray beam is again turned on, the same will be directed to its initial or normal position above the scale I! preparatory to another operation of the relaxation genas erator I. Since the path or line 28 is produced twenty-five or more times per second, persistence of vision on the part of the observer win cause this path or line to appear continuous.

measured by the tube is an accurate indication of the height of the craft. 1

Similarly, as soon as the receiver 30' receives the reflected wave sent out by transmitter 4', the diode 34' is caused to' operate and create a voltage-drop across the resistor 35', charging the 5 condenser 36' and depressing the voltage oncontrol grid so that the cathoderay beam passing between plates 2| is cut ofl, the length of the fluorescent line 28' indicating on scale 29' the distance of the craft from theearth as measm ured along theline '40 in Fig. 2. Inasmuch as I go have-sufficient gain to give'the desired control signal for shutting off the corresponding beam of tube l1. Thus, by making the angle 0 equal 60, the distance 40 would be twice the length of the distance ll in Fig. 2 in the event that the g5 earth's contour 42 is horizontal and the craft is flying on an even keel. By adjusting resistor l4 so as to make scale 29" one-hall. that of scale 29, the two luminous paths" and 28' will have the same length as long as the ship is flying above flat country. In other words, these lines 28 and 28 will have their tops level with each other. However, as soon as the contour of the earth in advance of the craft changes, this will no longer be true, the depressing of line, 28' below line 28 indicating that the contour of the earth is rising, as shown in Figs. 2 and 3. Likewise, should line 28' become longer than line 28, it will serve to indicate that the-contour of the earth is falling. Thus, the pilot, in using the device of the present invention, can tell at all times the condition of the earth's contour ahead of him and can accordingly control his craft so as to either fly over obstacles or avoid the same by turning to one side or the other. and

' 5 hence preventing crashes.

By varying the magnitude of the resistors H or H, the rate of upward movement of the cathode ray beams may be varied, thereby varying the scales 2!! and 29' so that successive indicationsv thereof may be caused to indicate, for example,

10, 100 or 1000 foot intervals, whichever is desired.

As many changes could be made in the above construction and many apparently widely. diflerent embodiments of this invention could be made without departing from the scope. thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A radio contourmeter for aircraft, compris- 7 ter, the operation of said indicator serving as an indication of the height of the craft above the earth and further indicating the'rel'ative" e1evation of the terrain in advance of the craft.

2, In an instrument of the character described for aircraft, radio transmitting means including 6 directive antennae disposed tofdirect ultra high frequency pure carrier radiation inselected directions only from said craft, radio receiving means having directive receiving antennae disposed to respectively receive reflected radiation returning 1o from said directions, means for causing said transmitting means to operate momentarily at regular intervals of time tocause said directional antennae to deliver pure carrier radiation in the form of beams extending in said selected direcl5 tions from the aircraft, a cathode ray tube. said last named means also serving to vary potentials on the deflecting plates of said cathode ray tube for use intiming the periods required for the electromagnetic radiation from said transmitting 20 means directive antennae to reach the earth and return by reflectionto said receiving means, said receiving means being connected to said cathode ray tube and operating to determine the end of each of said timing operations, whereby said 25 cathode ray tube indicates the changing contour of the earth below and in advance of the craft and the distances of the craft therefrom.

3. In a radio contourmeter for aircraft, a pair of ultra high frequency transmitters having di- 30 rectional antennae, one of said antennae being directed downwardly for transmitting beam type electromagnetic energy directly down for reflection from a, limited portion of the terrain below,

and the other downwardly and forwardly for a ceiving antennae for receiving reflected radiation initially transmitted from said transmitters and reflected from said separated portions of the terrain, said receivers being connected to the control 50 grids of said cathode ray tube for shutting off said beams, the visible paths traversed by said beams being measures of the height of'the craft with respect to the terrain below and in advance of the craft. u

4. In a radio contourmeter for aircraft, ultra high frequency transmitters having highly directive antennae, relaxation generators for causing said transmitters to operate intermittently and but momentarily so that said antennae send out o beams of electromagnetic energy in selected directions from the craft, a cathode ray tube adapted to produce as many beams moving in parallel planes as there are transmitters, said relaxation generators being connected to said as cathode ray tube and serving respectively to cause the respective beams of the tube to move over the face thereof upon operations of the respective transmitters, and radio receivers having highly directive antennae for receiving reflected radial0 0 I tion initially transmitted from said transmitters below, said receivers being connected to said cathode ray tube for shutting off said beams, the

"paths produced by said beams on the face of 1 said tube being measures of the height or the craft with respect to the earth below and in ad- 7 vance of the craft.

5. A radio contourmeter as defined in claim 4, wherein saidrelaxation generators are provided with means for varying the rate of movement oi the two beams to accordingly vary the reading scales of the tube.

.6. A change of contour indicating device for aircraft comprising a plurality of transmitting 15 of which antennae directs the waves ahead of the craft, a plurality of receiving means for directionally receiving the reflected waves from the ground, and indicating means cooperating with said transmitting and receiving means for indicating the comparative distance 01 the craft from 5 the points of reflection of said waves on the ground.

7. A radio-countourmeter as deflned'in claim 4,

wherein said cathode ray tube is controlled so PAUL B. HUNTER. 15 

